Accumulated Other Comprehensive Loss - Net Change and Ending Balances for Various Components of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 91,806	$ 84,999
Net change	(1,755)	(458)
Ending Balance	91,930	88,483
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(14,322)	(11,371)
Net change	(2,614)	(856)
Ending Balance	(16,936)	(12,227)
Unrecognized Employee Benefit Costs [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(40,563)	(57,652)
Net change	511	419
Ending Balance	(40,052)	(57,233)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	277	589
Net change	348	(21)
Ending Balance	625	568
Less: Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	498	261
Net change	28	34
Ending Balance	526	295
Accumulated Other Comprehensive Loss Attributable to Ampco-Pittsburgh [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(55,106)	(68,695)
Net change	(1,783)	(492)
Ending Balance	(56,889)	(69,187)
Total Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(54,608)	(68,434)
Net change	(1,755)	(458)
Ending Balance	$ (56,363)	$ (68,892)